Laboratory or industrial type furnaces which are inherently designed for use on the ground cannot be simply modified for adoption for use in space. Restraints on these ground furnaces are imposed by the host vehicle, such as minimum size and weight, power availability, mechanical loading and other safety considerations. The known prior art of utilizing furnaces in space processing facilities has been limited in the amount of thermal control and sample process functions they offer. The furnace systems used on the Skylab were limited to heating a sample on one end and passively cooling it on the other end. Additionally, these furnaces were limited in their processing functions by having only one heating zone, i.e., having all furnace cavities heated to the same temperature with the same heating element. This requires the furnace to process the same experiment in all three cavities. Furthermore, since these furnace systems were passively cooled, they did not provide any active coolant agent such as a gas or liquid.
Representative of these prior art furnaces is U.S. Pat. No. 3,647,924 issued to John R. Rasquin for a high temperature furnace for melting materials in space. While this furnace has been designed for its use in the vacuum and zero gravity environment of outer space, it only contains one cavity with one heating element and does not utilize an automatic control system capable of remotely monitoring the experiment sample through various processing stages. Furthermore, the furnace of Rasquin is not designed to withstand rocket lift-off vibration loads as high as 30 G. Additionally, since Rasquin contains only a single heating element, it is not capable of establishing a thermal gradient and therefore its experimental capacities are much more limited than those capable in the present invention.
Other prior art patents relating either to furnaces in general, or heating in outer space, are U.S. Pat. Nos. 2,345,181; 2,647,826; 2,850,597; 2,944,500, 3,171,346; 3,548,062; 3,736,360; 3,737,553 and 3,860,222. The majority of these references relate to industrial heaters which are designed in such a manner that they could not be used aboard an outer space vehicle. For the most part, these inventions require at least a 110 volt AC power supply to furnish the power for the furnace operation and control. This required power is much too great to be supplied by the power supply on the rocket. The furnace of the present invention is designed to be as light as possible, as small as possible and require minimum power along with withstanding a wide range of vibration, acceleration and shock loads both at room temperature and at a maximum operating temperature. The referenced prior art inventions cannot be modified or designed to withstand these vibrations and be used on an inflight rocket.